1. Field of the Invention
The present invention relates to a process for treating waste gases containing ClF.sub.3. More particularly, the present invention relates to a method by which waste gases that result from the step of dry cleaning the inside surfaces of processing apparatus and related jigs in semiconductor device fabrication with ClF.sub.3 can be rendered harmless by removing not only ClF.sub.3 but also acidic gases including SiCl.sub.4, SiF.sub.4, Cl.sub.2 and F.sub.2.
2. Description of the Prior Art
In order to meet the recent demand for reducing the feature size of VLSIs and improving the efficiency of their fabrication, there has been a growing need for auto-cleaning the inside surfaces of CVD and PVD apparatus as well as related jigs in the fabrication of semiconductor devices. In this respect, the effectiveness of ClF.sub.3 has attracted the attention of manufacturers since it is capable of plasmaless cleaning at low concentrations and temperatures. However, ClF.sub.3 has a very high level of toxicity (TLV-TWA=0.1 ppm) and it is strongly desired to establish a method of rendering ClF.sub.3 harmless. Common methods for making ClF.sub.3 harmless include wet systems using a scrubber with aqueous alkaline solutions and dry systems using soda lime or activated alumina.
In the prior art, ClF.sub.3 cannot be completely removed by single use of treating agents such as alkali agents or activated alumina. In addition, chlorine oxides are released by reaction with the treating agents used. Further, acidic gases such as SiCl.sub.4, SiF.sub.4, Cl.sub.2 and F.sub.2 that are discharged together with ClF.sub.3 can only be partially removed, or they can only be removed in very small amounts.